Measurement of the axial residual stresses using the initial strain approach

Traditionally the unknown variables to be estimated in residual stress meas urement are based on the approximation of the stresses. In this paper an al ternative approach is presented in which the initial strain is used as the unknown variable to be estimated in the measurement. A useful feature of th e approach is that it does not require the measurement to be made on the or iginal part if the stress is uniform in the axial direction. Instead, the o riginal residual stress call be computed once the initial strains are obtai ned from a specimen removed from the original part. This approach is incorp orated into two recently developed methods: the crack compliance method and the single-slice method for measurement of the axial stress in plane strai n. Experimental validation shows that the approach based on initial strains leads to a result that agrees very well with the analytical prediction.